Batteries are commonly used in a wide array of applications such as automobiles, boats, motor homes, fork lifts, electronic wheelchairs, etc. The batteries used in such applications may, typically, be charged, discharged, and recharged again. In this manner, a single battery may serve as a source of electrical current for a relatively long period of time.
Although a battery may be charged and discharged many times, inefficient use of the battery can significantly shorten the life of the battery. In general, the service life of a battery is determined by the amount of capacity (ampere-hours) or energy (watt-hours)delivered by the battery. Thus, each battery has an expected lifetime that is limited to a given amount of energy or capacity in discharge. For large discharge applications, expected lifetime is a number of cycles of ampere-hours (or watt-hours). For shallow discharge applications, the capacity (or energy) is the quantification of dynamic and fluctuating cycling. One charge and discharge of a battery constitutes a single battery cycle. Thus, each battery has an expected lifetime that is limited to a given number of cycles. Improper battery cycling procedures can severely limit the life of a battery. Perhaps most importantly, discharging the battery to extremely low voltages can damage the battery and reduce the expected battery life. Additional factors such as temperature, storage period and discharge load may further reduce the expected battery lifetime. Over the last century, battery technology has experienced dramatic improvement, yet battery energy management remains an area characterized by uncertainty. In modern applications, where the remaining capacity is crucial (such as electric wheelchairs), battery users frequently overcharge, inefficiently cycle, and prematurely replace their batteries because accurate, affordable systems to find the optimal battery for a desired usage demand are unavailable. As battery systems become more complex, the penalty incurred by poor energy management increases.
The life and reliability (L&R) of a battery is generally quoted as the number of cycles or years. L&R is typically determined through laboratory analysis. The L&R of a battery is sensitive to the manner and temperature in which a battery is used. However, L&R assessment is not made in view of the conditions under which the battery will actually be used. Another difficulty encountered is that there is no efficient system to optimize, assess or design devices, which require batteries, based on the particular battery requirements.
The disadvantages associated with current, efficient, battery usage techniques have made it apparent that a new technique for optimizing battery use is needed. Given a particular device requiring a battery, the new technique should find a match for the device and the optimal battery for that device. The new technique should also apply life and reliability data to efficiently match the device and battery. The present invention is directed to these ends.